1 files changed, 87 insertions, 0 deletions
diff --git a/EDK/Foundation/Library/EfiCommonLib/Ia32/Log2.asm b/EDK/Foundation/Library/EfiCommonLib/Ia32/Log2.asm
new file mode 100644
index 0000000..167086e
--- /dev/null
+++ b/EDK/Foundation/Library/EfiCommonLib/Ia32/Log2.asm
@@ -0,0 +1,87 @@
+      TITLE   Log2.asm: 64-bit integer logarithm function for IA-32
+
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2004, Intel Corporation                                                         
+; All rights reserved. This program and the accompanying materials                          
+; are licensed and made available under the terms and conditions of the BSD License         
+; which accompanies this distribution.  The full text of the license may be found at        
+; http://opensource.org/licenses/bsd-license.php                                            
+;                                                                                           
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             
+; 
+; Module Name:
+;
+;   Log2.asm
+; 
+; Abstract:
+; 
+;   64-bit integer logarithm function for IA-32
+;
+;------------------------------------------------------------------------------
+
+  .686P
+  .XMM
+  .MODEL SMALL
+  .CODE
+
+Log2 PROTO C  Operand: QWORD
+
+Log2 PROC C   Operand: QWORD
+
+;------------------------------------------------------------------------------
+; UINT8
+; Log2 (
+;   IN UINT64   Operand
+;   )
+;
+; Routine Description:
+; 
+;   Calculates and floors logarithms based on 2
+;
+; Arguments:
+;
+;   Operand - value to calculate logarithm
+;  
+; Returns:
+;
+;   The largest integer that is less than or equal
+;   to the logarithm of Operand based on 2 
+;------------------------------------------------------------------------------
+
+  push   ecx
+  
+  mov    ecx, 64
+  
+  cmp    dword ptr Operand[0], 0
+  jne    _Log2_Wend 
+  cmp    dword ptr Operand[4], 0
+  jne    _Log2_Wend 
+  mov    cl, 0FFH
+  jmp    _Log2_Done
+  
+_Log2_Wend:
+  dec    ecx
+  cmp    ecx, 32
+  jae    _Log2_Higher
+  bt     dword ptr Operand[0], ecx
+  jmp    _Log2_Bit
+  
+_Log2_Higher:
+  mov    eax, ecx
+  sub    eax, 32
+  bt     dword ptr Operand[4], eax
+  
+_Log2_Bit:
+  jc     _Log2_Done
+  jmp    _Log2_Wend
+      
+_Log2_Done:
+  mov    al, cl
+  pop    ecx
+  ret
+    
+Log2 ENDP
+
+END